Wireless beacons are hardware transmitter devices that broadcast information to other wireless devices in their vicinity. They have recently become very popular in numerous emerging applications such as Internet of Things (“IoT”), Augmented Reality (“AR”), wearables, health care, and home automation, among others. The information broadcasted can range from location data, ambient data, movement or orientation data, or any other information capable of being transmitted under a wireless communications protocol or standard over relatively short distances (e.g., within 15 meters). An example wireless standard for wireless beacons is the Bluetooth Low Energy (“BLE”) standard, designed to provide considerably reduced power consumption and cost. BLE beacons are usually powered by coin cell batteries and designed to guarantee 1-3 years of lifetime. They are also designed to operate within a dedicated frequency range (e.g., between 2.4 and 2.485 Hz) and output a low maximum power (e.g., 10 mW for the current BLE v4.2 specification), which is 10× lower than the WiFi transmission power specified by the FCC.
The power-saving features of BLE beacons constrain their range and also make their broadcast signals more susceptible to path loss caused by blockage of signal propagation. Further, in order to coexist with WiFi and other RF signals that operate in the same frequency range, BLE specifications incorporate narrow bandwidth and frequency hopping, thereby making BLE broadcast signals subject to frequency-selective fading. Like other RF signals, BLE beacon broadcast signals suffer from signal degradation. Multipath fading occurs when RF signals reach the receiving antenna via multiple different paths, further exacerbating the BLE signals' strength. In addition, to maximize battery life, BLE beacons are often non-connectable (i.e., set to broadcast only), which largely limits their interaction with surrounding mobile devices.